Electrical boxes are often mounted in the walls or ceilings of buildings for coupling and supporting wiring devices, lighting fixtures, ceiling fans and other types of devices. In particular, electrical boxes provide an isolated space for electrical connections between the wiring device or fixture and the wiring of the building. These electrical boxes are typically coupled to either one or more structural supports such as studs or joists. Some electrical boxes are provided with integral brackets for directly attaching the electrical box to the support member, while other electrical boxes are coupled to a separate hanger or support assembly which extends between a pair of adjacent structural supports.
In most applications, fixtures, such as, ceiling fans, heavy lights or other similar devices, are directly mounted to the electrical box. The standard mounting brackets or assemblies for securing electrical boxes to a structural support are typically inadequate for supporting ceiling fans and other heavy electrical fixtures. Failure to properly mount the electrical box can sometimes result in the ceiling fan or heavy fixture falling, and thereby, causing personal injury or damage to the building.
Several mounting assemblies have been proposed in the past for securing and supporting ceiling fans or other fixtures between a pair of structural supports. These assemblies are usually attached to the ceiling joists by a brace, a bar hanger or other suitable member extending between the joist. Many of these assemblies are not adjustable for different spacings of joists, while other assemblies do not provide continuous adjustability of mounting the electrical box to the assembly.
One type of mounting assembly includes a pair of telescoping pipes or hollow rods which are expanded to engage adjacent structural supports or joists. The rods can be coupled by a threaded coupling so that rotation of one rod with respect to the other causes the assembly to expand literally until the distal ends of the rods frictionally engage the structural supports or ceiling joists. Other mounting braces may also include sharp prongs or teeth which are driven into the joists by the force applied by the rotation of the rods. Examples of such mounting assemblies are disclosed in U.S. Pat. Nos. 2,316,389 to Atkinson; 2,809,002 to Rudolph; 2,945,661 to Appleton; 3,163,386 to Collins; 4,050,603 to Harris et al.; 4,463,923 to Reiker; 4,538,786 to Manning; 4,645,158 to Manning; 4,659,051 to Propp et al.; 4,682,452 to Propp et al.; Re. 33,147 to Reiker; 4,909,405 to Kerr, Jr.; 5,044,582 to Walters; 5,150,868 to Kaden; and 5,330,137 to Oliva.
While these prior ceiling mounting braces are adequate in many applications, they typically do not provide for accurate positioning of different depths of electrical boxes. In particular, in mounting bracket applications, it is desirable for the front of the electrical box after being mounted between a pair of studs or structural support members to be flush with the front or finished side of the dry wall or sheet rock applied to the studs. Therefore, electrical boxes of different depths must be set back from the exterior surface of the dry wall or sheet rock so that the open end of the electrical box remains substantially flush with the outer surface of the sheet rock or dry wall.
Although the above-mentioned mounting brackets can be generally effective and provide adequate strength, they are typically not easy to install with a wide variety of boxes such that the open end of the electrical box will be flush with the plasterboard or wallboard. Accordingly, there is a continuing need in the industry for a simple and effective adjustable hanger bar capable of accommodating a wide variety of electrical boxes. This invention addresses this need in the art along with other needs in the art which will become apparent to those skilled in the art from this disclosure.